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Chapter 8 Quiz 2012-2013
I. MULTIPLE CHOICE: Choose the one best answer each. Assume g = 10 m/s2.
(2 points each).
1. The momentum of an object is proportional to its
A. Velocity
B. Mass
C. Mass x Velocity
D. All of the above
E. None of the above
2. Impulse is equal to the change of
A. Velocity
B. Mass
C. Force
D. Momentum
E. Force x Velocity
3. In order to double the momentum of an object, its velocity must change by a factor:
A. x 2
B. x 1/2
C. x 4
D. x 1/4
4. When a force F is applied to an object on a frictionless surface over a time interval, a
change in velocity is created. If the time interval the force is applied increases by a
factor of 2, what applied force below would yield the same change in velocity for the
object?
A. 2F
B. F/2
C. 4F
D. F/4
5. One egg is thrown against a solid wall, while a second egg is thrown against a hanging
bed sheet. Both eggs have the same initial velocity (35 miles per hour) and the same
final velocity (zero miles per hour). Which egg experiences a greater change in
momentum?
A. The egg stopped by the wall.
B. The egg stopped by the hanging sheet.
C. Both eggs experience the same change in momentum.
6. One egg is thrown against a solid wall, while a second egg is thrown against a hanging
bed sheet. Both eggs have the same initial velocity (35 miles per hour) and the same
final velocity (zero miles per hour). Which egg experiences a greater force?
A. The egg stopped by the wall.
B. The egg stopped by the hanging sheet.
C. Both eggs experience the same force.
7. Which has the most momentum below?
A. a mass of 5.0 kg moving at 0.0 m/s
B. a mass of 2000 g moving at 500.0 cm/s
C. a weight of 30 N moving at 4.0 m/s
D. a mass of 1.5 kg moving at 6.0 m/s
8. Mass M1 moving with a speed vi collides with stationary mass M2. After the collision,
the masses are interlocked and moving with a speed of vi/3. Which equation below
correctly describes the relationship between M1 and M2?
A. M2 = 2M1
B. M1 = 2M2
C. M2 = 3M1
D. M1 = 3M2
9. A ball moving to the left strikes a wall at a speed of 4 m/s and rebounds to the right at
a speed of 2 m/s. What is the change in velocity v of the ball?
A. 0 m/s
B. 2 m/s
C. 4 m/s
D. 6 m/s
E. 8 m/s
10. A 1,200-kilogram car traveling at 10.0 meters per second hits a tree and is brought to
rest in 0.10 second. What is the magnitude of the average force acting on the car to
bring it to rest?
A. 1.2 × 102 N
B. 1.2 × 103 N
C. 1.2 × 104 N
D. 1.2 × 105 N
E. 1.2 × 106 N
II. PROBLEMS: On a separate sheet of paper, show your
your work and box your answer.
(5 points each:
Starting equation:
Work and correct answer:
Boxed answer:
starting equation(s), show
1 point
3.5 points
0.5 points)
1. Calculate the momentum of a 2250-kg elephant charging a hunter at a speed of 7.00
m/s.
2. A hockey puck has a mass of 0.122 kg and is at rest. A hockey player makes a shot,
exerting a constant force of 25.0 N on the puck for 0.180 s. With what speed does
the puck head toward the goal?
3. How long must a 12.0 N force be applied to a 4.00 kg block sitting at rest on a
frictionless surface to increase its velocity to 4.40 m/s?
4. A 65.0-g arrow leaves a bowstring at a velocity of 54 m/s.
A. What is the impulse on the arrow?
B. What is the average force that the string exerts on the arrow if the string is in
contact with the arrow for 9.0 x 10-3 s?
5. A 1.90-kg falcon catches a 0.600-kg dove from behind in midair. What is their velocity
after impact if the falcon’s velocity is initially 26.0 m/s and the dove’s velocity is 6.00
m/s in the same direction?
BONUS: A ballistic pendulum was used to measure
the speed of bullets before electronic
timing devices were developed.
h
Suppose a 14.0-g bullet is fired and imbeds in a 2.50-kg wooden block. The block
and bullet then swing up to a maximum height of 18.0 cm above the starting
position. Find the initial velocity of the bullet.